Soaring ER CT use stirs appropriateness concerns

January 1, 2007

Soaring use of CT in the emergency room gets cheers in some corners and jeers in others. Radiologists heard from both sides of the appropriateness debate at the RSNA meeting.

Soaring use of CT in the emergency room gets cheers in some corners and jeers in others. Radiologists heard from both sides of the appropriateness debate at the RSNA meeting.

"CT has become the most important diagnostic imaging modality in the emergency department. Although it has great diagnostic utility, it also represents a lot of radiation exposure to patients and significant healthcare costs," said Dr. Joshua Broder, an assistant professor of emergency medicine at the University of North Carolina in Chapel Hill.

Researchers at Broder's institution examining CT utilization in the ER from 2000 to 2005 found dramatic growth for studies involving a range of organs. Cervical spine CT use shot up by 463%, albeit from a relatively low baseline. The number of admissions rose by only 13%, and severity of injury and illness changed little.

"Utilization outpaced growth in volume. There has been a rise in use of CT as well as increased availability of the study and desire for diagnostic certainty. It remains to be seen if outcomes improve," Broder said.

Data on the increased use of CT in the emergency department are available for the Medicare population and for some specific indications. But the exact extent has not been fully investigated by study type and patient age.

In the North Carolina study, a total of about 200,000 patients were admitted over a five-year period. More than 46,000 CT studies were performed on 27,000 of these patients.

Researchers found the following increases:

  • head CT, up by 51%;

  • abdominal CT, 72%;

  • chest CT, 226%; and

  • miscellaneous (e.g., extremities and face), 132%.

The cervical spine results were particularly striking. One major national study indicates a prevalence of 2% for spinal fractures in the ER, and it is doubtful that the large proportional increase was matched by prevalence of injury, Broder said.

"It is fairly unlikely that the 463% increase resulted in finding lots of spinal injuries that would [otherwise] have been missed," he said.

Researchers also see a bundling effect in CT utilization. In the study, doctors who ordered a head CT, for example, were sometimes inclined to order a cervical spine CT as a precautionary measure, even if the second exam was not directly indicated.

"Utilization in one segment feeds off the others," Broder said.

Attention has increased to the need for monitoring utilization in pediatrics to minimize risks of radiation exposure, but the same concern for younger adults, who are also at risk, has been lacking. The age range for the patients in the North Carolina study spanned from mid-40s to early 50s, and utilization rose greatly regardless of age, he said.

An analysis of repeat scans of the same body part showed that 2% of those who had a chest CT underwent repeated chest CT scans on three or more subsequent visits. Of about 10,000 patients who had abdominal CT, 4% underwent a repeat abdominal CT scan on three or more subsequent occasions.

The study was limited in its analysis of effects on patient management and outcomes. Audience members at the RSNA session pointed out that negative CT scans can save unnecessary hospital stays and that underutilization of CT can be dangerous and counterproductive.

Another study urged greater use of whole-body CT based on improved outcomes. Guidelines indicate that use of whole-body CT is appropriate as a secondary tool after trauma resuscitation, but it may also have value as the first study. Researchers at Munich University Hospital found that whole-body multislice CT should be used as the first screening study in major trauma cases, including unstable patients.

Dr. Markus Koerner, a resident in clinical radiology at the hospital, presented results of a study of almost 5000 major trauma patients seen between 2002 and 2004. Researchers assessed injury severity and survival rates for patients who received single-organ versus whole-body CT.

Depending on the analysis model used, whole-body CT helped reduce mortality rates 13% to 26%. Liberal use of whole-body CT as a primary screening study increases the rate of false negatives, but the significant reduction in mortality more than makes up for this disadvantage, Koerner said.